Underground mining (e.g., coal mining) typically necessitates the cutting of intersecting passageways throughout the mine. These intersecting passageways are often arranged in a grid pattern, with the passageways intersecting at right angles. In addition to providing access, the passageways are also used for ventilation purposes. Some passageways are used to deliver fresh air into the mine while others to expel contaminated air from the mine. Where a fresh air passageway intersects a contaminated air passageway it is necessary to prevent mixing of the two air streams.
An overcast (also referred to as an undercast) is a structural system that is typically utilized in a mine or tunnel ventilation system. The structure is constructed in a mine intersection for the purpose of preventing the mixing of the ventilation air and contaminated air at an intersection. Overcasts, however, can be time-consuming to assemble in place, and must be sized for the particular intersection. In addition, it can be difficult to provide sufficient sealing between the overcast and the mine ribs to prevent or limit mixing of ventilation air and contaminated air.
While a variety of devices and techniques may exist for providing overcast structures in mines, it is believed that no one prior to the inventors have made or used an invention as described herein.
The drawings are not intended to be limiting in any way, and it is contemplated that various embodiments of the invention may be carried out in a variety of other ways, including those not necessarily depicted in the drawings. The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention; it being understood, however, that this invention is not limited to the precise arrangements shown.